Method and system for controlling an eye tracking system

Abstract

There is provided a method, system, and non-transitory computer-readable storage medium for controlling an eye tracking system (200) to obtain a first image (500) captured under active illumination by at least one infrared, IR, illuminator (112, 113) associated with the eye tracking system (200) and at a current exposure setting, using the image sensor device (110); and, if at least one eye (100, 120) is depicted in the first image (500): define at least one region of interest, ROI, (501, 502, 503, 504) from the first image (500) comprising a group of pixels in the first image (500) representing at least a part of the depicted at least one eye (100, 120); determine a respective intensity value for each of the at least one ROI (501, 502, 503, 504); determine a second exposure setting by adjusting at least one exposure parameter of the image sensor device (110) based on the determined intensity value, or values, for the at least one ROI (501, 502, 503, 504); and set the current exposure setting to the second exposure setting.

The invention claimed is: 
     
       1. A computer implemented method for controlling the exposure setting of an image sensor device associated with an eye tracking system to enable eye tracking, the image sensor device being sensitive to IR light, wherein the method comprises:
 obtaining, in the eye tracking system, a first image, wherein the first image is captured under active illumination by at least one infrared, IR, illuminator associated with the eye tracking system and at a current exposure setting, using the image sensor device; 
 determining, using processing circuitry comprised in the eye tracking system, if at least one eye is depicted in the first image, wherein determining if at least one eye is depicted in the first image comprises detecting in the first image at least part of an eye illuminated by IR light from the at least one IR illuminator, wherein said at least one part of an eye comprises at least one glint, at least one pupil, a part of at least one iris, a part of at least one sclera, or a part of at least one eye lid; 
 if at least one eye is depicted in the first image;
 defining, using the processing circuitry, at least one region of interest, ROI, from the first image comprising a group of pixels in the first image representing at least a part of the depicted at least one eye; 
 determining, using the processing circuitry, a respective intensity value for each of the at least one ROI based on intensity values of the group of pixels in the ROI; 
 determining a second exposure setting by adjusting, using the processing circuitry, at least one exposure parameter of the image sensor device based on the determined intensity value, or values, of the at least one ROI; and 
 setting, using the processing circuitry, the current, exposure setting to the second exposure setting; 
 
 and further comprising:
 after setting the current exposure setting to the second exposure setting, obtaining, using the image sensor device, a second image captured using the image sensor device, the second image being captured under active illumination by at least one infrared, IR, illuminator associated with the eye tracking system; 
 wherein the at least one IR illuminator is illuminated during an entire exposure time of the image sensor. 
 
 
     
     
       2. The method of  claim 1 , wherein detecting in the first image, using the processing circuitry, at least part of an eye comprises detecting at least one glint caused by IR light from the at least one IR illuminator or at least one pupil illuminated by IR light from the at least one IR illuminator. 
     
     
       3. The method of  claim 1 , wherein defining, using the processing circuitry, at least one region of interest from the first image comprises defining a first region of interest, ROI, for a first eye depicted in the first image and a second region of interest, ROI, for a second eye depicted in the first image. 
     
     
       4. The method of  claim 1 , wherein determining the respective intensity value of each of the at least one ROI comprises applying a histogram to the intensity values of all or a selection of the pixels in the ROI. 
     
     
       5. The method of  claim 1 , wherein deter lining if at least one eye is depicted in a first image comprises detecting, using the processing circuitry, pixel representing a glint or at least a part of one or more of the iris, the pupil, the sclera, or the eye lid of the least one eye. 
     
     
       6. The method of  claim 1 , wherein the at least one exposure parameter of the image sensor device comprises gain and wherein adjusting the at least, one exposure parameter comprises applying a gain to be multiplied to the pixel intensity values of images captured using the image sensor device. 
     
     
       7. The method of  claim 1 , wherein the at least one exposure parameter of the image sensor device comprises exposure time and wherein adjusting the at least one exposure parameter comprises adjusting the exposure time to be applied when capturing images using the image sensor device. 
     
     
       8. The method of  claim 1 , wherein the at least one exposure parameter of the image sensor device comprises skipping or binning and wherein adjusting the at least one exposure parameter comprises adjusting a skipping or binning read-out scheme for the image sensor device. 
     
     
       9. An eye tracking system, the system comprising an image sensor device being sensitive to IR light and processing circuitry, wherein the processing circuitry is configured to control the exposure setting of the image sensor device, by:
 obtaining a first image, wherein the first image is captured under active illumination by at least one infrared, IR, illuminator associated with the eye tracking system and at a current exposure setting, using the image sensor device; 
 determining if at least one eye is depicted in the first image, wherein determining if at least one eye is depicted in the first image comprises detecting in the first image at least a part of an eye illuminated by  1 R light from the at least one IR illuminator, wherein said at least one part of an eye comprises at least one dint, at least one pupil, a part of at least one iris, a part of at least one sclera, and/or a part of at least one eye lid; 
 if at least one eye is depicted in the first image:
 defining at least one region of interest, ROI, from the first image comprising a group of pixels in the first image representing at least a part of the depicted at least one eye; 
 determining a respective intensity value for each of the at least one ROI based on intensity values of the group of pixels in the ROI; and 
 determining a second exposure setting by adjusting at least one exposure parameter of the image sensor device based on the determined intensity value, or values, for the at least one ROI; and 
 setting the current exposure setting to the second exposure setting; 
 
 and further comprising:
 after setting the current exposure setting to the second exposure setting, obtaining, using the image sensor device, a second image captured using the image sensor device, the second image being captured under active illumination by at least one infrared, IR, illuminator associated with the eye tracking system; 
 wherein the at least one IR illuminator is illuminated during an entire exposure time of the image sensor. 
 
 
     
     
       10. The system of  claim 9 , wherein the processing circuitry is configured to detect in the first image at least a part of an eye by detecting at least one glint caused by IR light from the at least one IR illuminator or at least one pupil illuminated by IR light from the at least one IR illuminator. 
     
     
       11. The system of  claim 9 , wherein the processing circuitry is configured to define a first region of interest, ROI, for a first eye depicted in the first image and a second region of interest, ROI, for a second eye depicted in the first image. 
     
     
       12. The system of  claim 9 , wherein the processing circuitry is configured to determine the respective intensity value for each of the at least one ROI by applying a histogram to the intensity values of all or a selection of the pixels in the ROI. 
     
     
       13. The system of  claim 9 , wherein the processing circuitry is configured to determine if at least one eye is depicted in a first image by detecting pixels representing a glint or at least a part of one or more of the iris, the pupil, the sclera, or the eye lid of the at least one eye. 
     
     
       14. The system of  claim 9 , wherein the at least one exposure parameter of the image sensor device comprises gain and wherein the processing circuitry is configured to adjust the at least one exposure parameter by applying a gain to be multiplied to the pixel intensity values of images captured using the image sensor device. 
     
     
       15. The system of  claim 9 , wherein the at least one exposure parameter of the image sensor device comprises exposure time and wherein the processing circuitry is configured to adjust the at least one exposure parameter by adjusting the exposure time to be applied when capturing images using the image sensor device. 
     
     
       16. The system of  claim 9 , wherein the at least one exposure parameter of the image sensor device comprises skipping or binning and wherein the processing circuitry is configured to adjust the at least one exposure parameter by adjusting a skipping or binning read-out scheme for the image sensor device. 
     
     
       17. The system of  claim 9 , wherein the processing circuitry is further configured to perform eye detection based on the second image, using the eye tracking system. 
     
     
       18. A non-transitory computer-readable storage medium storing instructions which, when executed by processing circuitry of a system, cause the system to:
 obtain a first image, wherein the first image is captured under active illumination by at least one infrared, IR, illuminator associated with the eye tracking system and at a current exposure setting, using the image sensor; 
 determine if at least one eye is depicted in the first image, wherein determining if at least one eye is depicted in the first image comprises detecting in the first image at least a part of an eye illuminated by IR light from the at least one IR illuminator, wherein said at least one part of an eye comprises at least one glint, at least one pupil, a part of at least one iris, a part of at least one sclera, and/or a part of at least one eye lid; 
 if at least one eye is depicted in the first image:
 define at least one region of interest, ROI, from the first image comprising a group of pixels in the first image representing at least a part of the depicted at least one eye; 
 determine a respective intensity value for each of the at least one ROI based on intensity values of the group of pixels in the ROI; and 
 determine a second exposure setting by adjusting at least one exposure parameter of the image sensor device based on the determined intensity value, or values, for the at least one ROI; and 
 set the current exposure setting to the second exposure setting; 
 
 wherein the instructions further cause the system to:
 after setting the current exposure setting to the second exposure setting, obtain, using the image sensor device, a second image captured using the image sensor device, the second image being captured under active illumination by at least one infrared, IR, illuminator associated with the eye tracking system; 
 wherein the at least one IR illuminator is illuminated during an entire exposure time of the image sensor.